In the related art, for example, mounting a slide fastener on an opening of clothes or bags and the like is generally used. The basic structure of a slider for a slide fastener is configured by three members of a slider body having upper and lower blades connected at the front ends with a predetermined gap by a diamond, a tab, and a tab holder that holds and allows the tab to move and rotate between the upper surface of the upper blade and the tab holder.
An example of such type of slider has been proposed by the applicant(s), as a slider for a slide fastener (see, for example, Patent Document 1). For the slider for a slide fastener described in Patent Document 1, as an example of the invention in the related art, FIG. 15 is a perspective view illustrating the state before assembling and FIG. 16 is a perspective view illustrating a modified example.
As illustrated in FIGS. 15 and 16, a tab holder 69 is fitted between a pair of column portions 61 and 62 installed at the front and rear portions on the upper surface of a slider body 60 in a snap type, by elastically deforming a cover body configured as the tab holder 69. A plane portion 73 is formed on the upper surfaces of the pair of column portions 61 and 62 and a sliding guide surface 74 that is smoothly inclined is formed from the end of the plane portion 73 to engaging portions 63 and 64 of the lower portion.
That is, as engaging portions 70 and 70 formed at both ends of the cover body slides along the sliding guide surface 74, the gap between the engaging portions 70 and 70 is increased, so that the engaging portions 70 and 70 are engaged with the engaging portions 63 and 64 formed at the column portions 61 and 62 and the tab holder 69 is fitted to the slider body 69. Further, a pintle 68 of a tab 67 may be held between the pair of column portions 61 and 62 and the tab holder 60.
In general, as the resin material of the cover body, relatively hard resin is used. Accordingly, even though the cover body is engaged and attached between the pair of column portions 61 and 62 by elastically deforming the cover body such that the gap between the engaging portions 70 and 70 formed at both ends of the cover body increases, and even though the cover body is returned in the direction in which the gap between the engaging portions 70 and 70 relatively decreases after engaging and attaching, the gap may not return to the previous gap before the elastic deformation.
In this state, slip is generated between the cover body and the pair of column portions 61 and 62, and when the tab 67 is operated, the cover body may be separated from the pair of column portions 61 and 62. In order to prevent that, in the slider for a slide fastener of Patent Document 1, as illustrated in FIG. 15, support walls 65 and 66 are installed at the sides of the column portions 61 and 62 to prevent slip in the left and right directions. Further, as illustrated in FIG. 16, protrusions 71 and 72 are formed on the upper surfaces of the column portions 61 and 62 and recessions where the protrusions 71 and 72 are fitted are formed on the inner side of the cover body which corresponds to the protrusions 71 and 72. In addition, a plane portion 75 is formed on the upper surfaces of the pair of column portions 61 and 62 and a sliding guide surface 76 that is smoothly inclined is formed from the end of the plane portion 75 to the lower engaging portions 63 and 64.
As described above, as the configuration where the support walls 65 and 66 are installed at the sides of the column portions 61 and 62 is employed, and as the configuration in which the protrusions 71 and 72 and the recessions are formed is employed, even if the gap between the engaging portions 70 and 70 is not returned to the previous gap before elastic deformation after the cover body is engaged and attached between the pair of column portions 61 and 62, slip between the cover body and the pair of column portions 61 and 62 can be prevented.
However, when the cover body is mounted on the pair of column portions 61 and 62, the engaging portions 70 and 70 of the cover body may come in contact with the plane portions 73 and 75 formed on the upper surfaces of the column portions 61 and 62, without coming in contact first with the sliding guide surfaces 74 and 76 formed at the column portions 61 and 62. In this case, even if the force pressing from above is fully applied to the cover body, the engaging portions 70 and 70 being in contact with the plane portions 73 and 75 cannot slide to the sliding guide surfaces 74 and 76. In particular, when this situation is generated during assembly work using an automatic assembly machine, when pressing force is forcibly applied to the cover body, the cover body may be broken.
However, when the slider body 60 or the cover body is made of a resin material, barrel polishing is generally performed on the formed product to remove burrs from the formed product. In this barrel polishing, a plurality of formed products are caused to hit each other and the formed products and an abrasive are caused to hit each other by putting the abrasive and the many formed products into a barrel and eccentrically rotating the barrel, thereby removing burrs sticking on the products in forming.
The thicknesses of the support walls 65 and 66 formed at the sides of the column portions 61 and 62 are small and edges of the support walls 65 and 66 individually protrude. Therefore, there is a problem in that a defect is generated in the support walls 65 and 66 by shock in barrel polishing, and particularly, a defect is generated at the edges or the portions around the edges are bleached. In particular, the smaller the size of the slider, the more the problem becomes remarkable.
In order to prevent a defect or beaching of the support walls 65 and 66 formed at the sides of the column portions 61 and 62 or the edges of the support walls 65 and 66, it is considered to increase the thicknesses of the support walls 65 and 66. However, in this case, the thicknesses of the support walls 65 and 66 are increased, but it is necessary to reduce the widths of the engaging portions 70 and 70 formed at the cover body.
That is, since the engaging portions 70 and 70 pass between the support walls 65 and 66 when the cover body is engaged and attached, when thicknesses of the support walls 65 and 66 are large, it is necessary to make the widths of the engaging portion 70 and 70 small. Therefore, in the engaging portions 70 and 70 of a cover body of which the width is small, a defect or bleaching of the engaging portions 70 and 70 is generated.
Further, as illustrated in FIG. 16, even in the case when the protrusions 71 and 72 are formed at the column portions 61 and 62, a defect or bleaching is generated in the protrusions 71 and 72. When a slider is manufactured by using a slider body 60 or a cover body where a defect or bleaching is generated, there is a problem in that attachment strength of the cover body is reduced. In addition, when the bleached portion is seen from the outside with naked eyes, there is a problem in terms of the external appearance.
In addition, when a resin product is bleached, the bleached portion is plastically deformed. Therefore, it is impossible to generate elastic deformation at the bleached portion, such that strength is correspondingly reduced. In addition, when tensile strength is applied to the bleached portion, the bleached portion is easily fully elongated.